China is overpopulated because Chairman Mao knew it was the only way to "win" a nuclear war. To have so many people that when the **** hits the fan, the amount of people you have left still vastly outnumbers the number of people your enemies have left.

Umm, the black death hit China in particular and Asia in general dozens of times. As a matter of fact it is thought to have originated in China and spread to Europe via the Silk Road. The outbreak in the 1300's, which affected all of Europe and Eurasia, is thought to have killed nearly a fourth of the population at that time, or roughly 100 million people, worldwide.